U.S. Pat. No. 3,122,137 describes a iontophoresis applicator applied on the orbit and not on the eye's surface and incorporating the current source. It does not propose means for keeping the eye's open and it is believed a large part of the product is also delivered into systemic circulation, due to a lack of precision in the placement of the device.
Iontophoresis devices in U.S. Pat. No. 5,522,864 and U.S. Pat. No. 6,101,411 should suffer from the same drawbacks.
U.S. Pat. No. 4,564,016 discloses a device having a small application surface (diameter 1 mm), applied on sclera and allowing very high current densities (between 50 and 2000 mA/cm2) for “focal iontophoresis”. These values should be toxic for concerned tissues, as confirmed in Maurice article in Ophthalmology (January 1986, vol 93, number 1) entitled Iontophoresis of fluorescing into the posterior segment of the rabbit eye.
Last, U.S. Pat. No. 6,154,671, discloses the principle of a device for delivering all kinds of active substances with safety and accuracy by iontophoresis, and answers then to most of the problematic of iontophoresis for ophthalmology.
More recently, U.S. Pat. No. 6,319,240 proposes an improvement of previous methods with a sealed reservoir applied on sclera (with a semi-permeable membrane on application face) under the eyelid. The semi-permeable membrane of this device is supposed to limit arcing effect between the electrode and the eye's surface that could occur due to the limited thickness and small surface of the device.
U.S. Pat. No. 6,442,423 describes a device where the product is cast in a gel and applied on cornea.
All the previous devices are implemented for delivering substances through the cornea or the sclera, in order to reach some determinate tissues.
Nevertheless, there is a need to improve the efficiency and decrease the time of application of some therapies implemented by iontophoresis.
For example, the therapy of glaucoma by iontophoresis needs to be improved.
Glaucoma is characterized by elevated intraocular pressure (IOP also known as ocular hypertension).
Glaucoma is classified as “open-angle glaucoma”, which results from decreased permeability of the aqueous humor through the trabecular meshwork, or as “angle-closure glaucoma” that results from shifting of the iris forward so that the anterior chamber angle is obstructed or congenital.
The congenital form of glaucoma rarely responds to therapy and is more commonly treated with surgery, but not by iontophoresis means.
It is known that elevated IOP can be at least partially controlled by administering drugs which either reduce the production of aqueous humor within the eye, such as beta-blockers or carbonic anhydrase inhibitors, or increase the outflow of aqueous humor from the eye, such as miotics or sympathomimetics.
These pharmacological approaches help restore the IOP to a normotensive state either by inhibiting the production of aqueous humor by the ciliary body, or facilitating trabecular or uveoscleral aqueous humor outflow.
To this aim, most of the drugs are administered topically (eye drops) to avoid associated systemic effects.
Although a wide variety of pharmaceutical treatments for lowering IOP are available for the glaucoma patient, these treatments are then limited either in terms of efficiency or side-effects.
Additionally, the previous iontophoresis devices are not specifically arranged for treating glaucoma.
A first object of the invention is to provide an ocular iontophoresis device which leads to an increase of the concentration of drugs delivered into the intraocular tissue, improving for example the treatment of glaucoma.
Another object of the invention is to reach the first object by providing a iontophoresis device arranged for decreasing the loss of medication before reaching the targeted tissues by limiting the risks of absorptions of the medication by intermediates and/or by increasing the guiding of the ionized medication, for then more sufficiently treating intraocular tissues.
Another object of the invention is to decrease the time necessary for administrating a determinate amount of substances while administering the same amount of active substances.